RESUMO
Enthalpy of solution measurements of four potassium salts in H2O were made in either an adiabatic or an isoperibol calorimeter or both. The following summarizes the measured and recommended values: [Table: see text] The value for KIO4 has been corrected for the hydrolysis of the periodate ion. The ΔC p = -(82.5 ± 4.3)J·mol-1·K-1 for the unhydrolysed reaction. For the reaction of KBr in H2O, ΔC p was measured as -(166.6 ± 7.2) J·mol-1·K-1 in the temperature range 298 K to 319 K. Measurements with the isoperibol calorimeter are also reported for the endothermic reaction of tris(hydroxymethyl)aminomethane, SRM 724a, in aqueous NaOH (0.05 mol·L-1). Comparisons of measurements by different calorimeters on the same samples reveal unidentified calorimetric errors for endothermic reactions which are greater than the imprecision of the measurements.
